Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description discloses useful behavioral details beyond the readOnlyHint and idempotentHint annotations: it states the data source (IRS Form 990 via ProPublica), the rate limit (30/minute), that no auth is required, and the key return fields. This gives the agent a complete risk and execution picture for a read-only operation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-organized and front-loads the core purpose before diving into output details and constraints. The report_feedback fallback adds length, but it is relevant operational guidance rather than filler. It remains concise enough for an agent to parse quickly.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description covers the data type, source, output fields, parameter behavior, rate limits, authentication requirements, relationship to a sibling tool, and a fallback path via report_feedback. With an output schema also present, this description is complete for an agent to select and invoke the tool correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents both parameters with formats, defaults, and ranges. The description repeats the years default and range but adds no new semantic information beyond what the schema already provides, so a baseline score of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly identifies the tool's action: providing a 5-year financial trend for US nonprofits, with specific data categories and output fields. It distinguishes itself from the sibling nonprofit_fetch_nonprofit_full_profile by positioning this tool as the multi-year complement, so an agent can tell which tool to use.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly connects this tool to nonprofit_fetch_nonprofit_full_profile and explains that it adds multi-year context, giving the agent a clear reason to select it. It does not fully enumerate when not to use it or provide alternative conditions for other nonprofit tools, but the context provided is sufficient for common use cases.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.